有關 "command rate" 這裡有詳細說明,
http://www.tomshardware.com/forum/1...-rate-explained
當中有一段有寫到DRAM模組PCB的品質(4層板,或6層板),
PCB品質會影響"command rate"在1T或2T時的穩定度,

"Other factors involve the distance of the DIMM slot from the memory controller and, most importantly, the quality of the DIMM's PCB. If a 4-layer PCB with its relatively high noise level is used, there is a fat chance of ever hitting a 1t command rate. A 6 layer PCB on the other hand has a better signal to noise ratio and can greatly speed up the decoding (on the level of the PCB). It is, therefore, not surprising that, even if the same chips are used on different DIMMs, the differences in the PCB will dictate whether the module is able to perform at a command rate of 1T or 2T" "